000
AXNT20 KNHC 082344
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SAT DEC 08 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL 
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN 
SECTIONS OF SOUTH AMERICA...AND THE ATLANTIC OCEAN TO THE 
AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION 
IS BASED ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS... 
WEATHER OBSERVATIONS...AND RADAR.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2245 UTC

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 8N12W 7N26W 5N41W 2N51W. CLUSTERS OF 
SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE MOVING OFF THE 
COAST OF SOUTH AMERICA S OF 8N BETWEEN 45W-56W. 

DISCUSSION...
GULF OF MEXICO...
SHORTWAVE UPPER TROUGH EXTENDS FROM CENTRAL ALABAMA INTO THE N 
GULF NEAR 27N90W LEAVING THE W GULF WITH NEAR WESTERLY UPPER 
ZONAL FLOW. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 
60 NM OF LINE FROM 26N88W TO OVER SE LOUISIANA NEAR 29N90W. AN 
UPPER RIDGE AXIS EXTENDS FROM THE CARIBBEAN ACROSS W CUBA AND 
THE FLORIDA PENINSULA TO THE GEORGIA COAST. A SURFACE RIDGE 
EXTENDS FROM A 1028 MB HIGH IN THE W ATLC OFF THE COAST OF 
FLORIDA/GEORGIA ACROSS FLORIDA TO MEXICO NEAR TAMPICO. DRY 
STABLE AIR COVERS THE REMAINDER OF THE GULF KEEPING SKIES RATHER 
CLEAR THIS EVENING. 

CARIBBEAN SEA...
BROAD UPPER RIDGE COVERS THE W CARIBBEAN W OF 75W ANCHORED BY AN 
UPPER HIGH OFF THE COAST OF NICARAGUA NEAR 13N82W ACROSS W CUBA 
NEAR 22N82W. DUE TO THE DRY STABLE AIR OVER THE AREA...UPPER 
LEVEL DIFFLUENCE IS ONLY ABLE TO GENERATE ISOLATED SHOWERS S OF 
14N W OF 80W. BROAD UPPER TROUGH COVERS THE E CARIBBEAN E OF 75W 
EXTENDING FROM THE W AND CENTRAL ATLC TO JUST INLAND OVER 
VENEZUELA. STRONG EASTERLY SURFACE FLOW DUE TO THE TIGHT 
PRESSURE GRADIENT INDUCED BY THE STRONG SURFACE RIDGE ACROSS THE 
ATLC IS GENERATING SCATTERED SHOWERS/WIDELY ISOLATED 
THUNDERSTORMS OVER THE NE CARIBBEAN N OF 14N E OF 71W INCLUDING 
PORTIONS OF HISPANIOLA TO THE LEEWARD ISLANDS. THE REMAINDER OF 
THE CARIBBEAN REMAINS MOSTLY CLEAR THIS EVENING. 

ATLANTIC OCEAN...
THE MOST SIGNIFICANT FEATURE THIS EVENING IS THE AREA ENE OF THE 
LEEWARD ISLANDS. THIS AREA OF DISTURBED WEATHER IS ASSOCIATED 
WITH AN UPPER LOW 18N56W AND A SURFACE TROUGH THAT EXTENDS ALONG 
55W FROM 14N-23N AT 08/2100 UTC. CLUSTERS OF SCATTERED MODERATE/ 
ISOLATED STRONG CONVECTION ARE WITHIN 200/225 NM OF LINE FROM 
12N41W ALONG 18N47W TO 20N57W. THIS SYSTEM IS BECOMING BETTER 
ORGANIZED WITH CONVECTION MAINTAINING OVER THE PAST SEVERAL 
HOURS. IT HAS BEEN MOVING SLOWLY WESTWARD AND COULD BRING 
SHOWERS/THUNDERSTORMS TO THE LEEWARD/VIRGIN ISLANDS OVER THE 
NEXT DAY OR TWO. OTHERWISE...AN UPPER RIDGE EXTENDING FROM THE 
CARIBBEAN OVER THE FLORIDA PENINSULA TO THE GEORGIA COAST AND 
COVERS THE FAR W ATLC W OF 75W. BROAD UPPER TROUGH COVERS THE 
REMAINDER OF THE W ATLC THROUGH THE CENTRAL ATLC FROM 50W-75W OF 
WHICH THE UPPER LOW AND SURFACE TROUGH MENTIONED ABOVE ARE 
EMBEDDED. A WEAK STATIONARY FRONT ALSO ASSOCIATED WITH THIS 
UPPER TROUGH DIPS S INTO THE REGION THROUGH 32N55W TO 28N60W. A 
CUT-OFF UPPER LOW IS IN THE E ATLC NEAR 28N35W COVERING THE AREA 
N OF 24N FROM 27W-44W. AN UPPER HIGH COVERS THE REMAINDER OF THE 
E ATLC ANCHORED OVER THE MADEIRA ISLANDS. BROAD SURFACE RIDGE 
COVERS THE ENTIRE ATLC INTO THE GULF OF MEXICO WITH A WEAKNESS 
ALONG THE FRONT MENTIONED ABOVE. A SERIES OF HIGHS AREA LOCATED 
ACROSS THE ATLC WITH A 1028 MB HIGH OFF THE COAST OF FLORIDA/ 
GEORGIA NEAR 31N81W...A 1027 MB HIGH JUST N OF BERMUDA...AND A 
1031 MB HIGH JUST ESE OF THE AZORES. 

$$
WALLACE